Aqueous detergent cleaning is often an integral part of the process of fabricating hybrid integrated circuits which are soldered to printed circuit boards. This is especially true when aqueous type solder fluxes are employed during the soldering operation. It has been found that when using aqueous detergent cleaners to remove solder flux residue, certain contaminants remain which result in an increased leakage current in the hybrid integrated circuit devices. This problem is particularly acute when silicone type encapsulants are employed for encapsulating the integrated circuit devices. Such encapsulants are generally relatively soft and of relatively low density and the contaminants become entrapped within the encapsulant layer. These contaminants may then eventually migrate to the surface of the device itself resulting in as much as an order of magnitude higher leakage current as compared to a control circuit which has not undergone the solder and detergent cleaning procedures. Not only is this higher leakage current undesirable, but the reliability of the devices may be diminished. Consequently, it would be advantageous to employ a cleaning method which removes not only the solder flux contaminants but, also other contaminants which tend to be left on the integrated circuit devices when employing aqueous detergent cleaning.